Display devices have become very important as a visual information communicating media in an information society. Cathode Ray Tube (CRT) display devices, which have been the main stream of the display devices, have problems, such as heavy weight and bulky volume.
Flat panel display devices include a liquid crystal display device (hereinafter, referred to as “LCD”), a field emission display (hereinafter, referred to as “FED”), a plasma display panel (hereinafter, referred to as “PDP”), and an electro-luminescence (hereinafter, referred to as “EL”), and the like. Most of these flat panel display devices are put to practical use, having significant market share in the display device market.
Such flat panel display devices include a plurality of thin film patterns, and each of the thin film patterns is formed by a photolithography process and an etching process.
FIG. 1 is a diagram illustrating a technique for forming a thin film pattern using the photolithography process and the etching process step by step.
First, a metal layer 4a is formed on a substrate for a flat panel display device 2 by a deposition technique such as sputtering, and the like. Next, the photolithography process including a photo-resist coating, an exposure, and developing processes is carried out to provide a photo-resist pattern 5. The metal layer 4a that did not overlap the photo-resist pattern 5 is removed by a dry or wet etching process using the photo-resist pattern 5 as a mask. Then, the photo-resist pattern 5 is removed by a stripping process to form a first thin film pattern 4.
A plurality of thin film patterns are disposed by the photolithography process, and the thin film patterns are electrically connected to each other or electrically insulated with each other by an electric contact of each of the thin film patterns as occasion demands. Herein, if each of the metal thin film patterns is electrically insulated, an insulating film 6 is formed on the substrate 2 provided with the first thin film pattern 4 as shown in FIG. 2. In this case, the insulating film 6 is formed of an inorganic insulating material such as SiNx and the like by a deposition technique such as PECVD, and the like.
On the other hand, if a gate pattern such as a gate electrode and a gate line, etc is formed at a liquid crystal display panel by the photolithography process and the etching process in FIG. 1, the wet etching process is used. However, the wet etching process is a method that a metal is exposed to an etchant to be selectively removed. The thin film pattern formed by the wet etching process has a drawback of a large error and deviation because time adjustment is difficult. Accordingly, if the gate pattern is formed by the wet etching process, the gate pattern is inadequately formed from time to time. As a result, when the liquid crystal display panel is complete, and then an image is realized, the gate pattern is not formed at the right position to generate a light leakage problem. Furthermore, although an insulating film is disposed, a step coverage generated by the gate pattern is maintained as it is. Thus, the data line provided on an insulating film may be broken by such step coverage.
The photolithography process and the etching process in FIG. 1 include the stripping process to remove the photo-resist pattern after the exposure process, the developing process, and the etching process are carried out. As a result, a manufacturing cost forming a thin film pattern is increased and a manufacturing time is also increased.